(583j) Li4Ti5O12 Pouch Cell Battery System for Selective Lithium Recovery from Aqueous Resources

Lithium shortage in the future has been predicted due to the surge on its demand especially for its use in electric vehicles (EVs). Consequently, recovery of lithium (Li) from other sources such as seawater, brine, and Li containing wastewater has been the center of interest in the energy sector. Discussions are directed towards aqueous sources to potentially alleviate the impending crisis. Ion-exchange using inorganic compounds and electrochemical processes are extensively investigated for Li recovery. However, ion exchange method has significant drawbacks such as slow kinetics and instability of materials. On the other hand, electrochemical Li recovery is challenged with its energy related requirements. However, this method is environmentally benign, has higher production rate and more amenable to scale-up for industrial applications.

Electrochemical Li recovery from aqueous solutions is an attractive alternative to adsorption methods. An electrochemical system that suppresses the high energy requirement and offer high purity Li compounds at a shorter amount of time is necessary. Herein, a modified Li₄Ti₅O₁₂ pouch cell battery system for electrochemical lithium recovery is presented. This hybrid reactor is composed of an anode in an organic electrolyte and Li-rich catholyte with Titanium foil or a porous carbon-based electrode as current collector. The two systems were integrated through an anode pouch cell assembly. It contained a lithium superionic conductor (LISICON) solid electrolyte in the open-structured top to separate the organic electrolyte from the aqueous electrolyte. Essentially, there were two reaction cells, one for Li capture and other for Li recovery. In Li capture cell, charging reaction of the system was the driving force to allow lithium ion (Li⁺) intercalation into the electrode inside the pouch cell. The Li-rich electrolyte was replaced with a suitable recovery solution to proceed with the Li⁺ release in a new cell. In the recovery cell, O₂ (from air) passing through the cathode reacted with Li⁺ to form LiOH. On the other hand, if Li₂CO₃ is desired as the end-product, LiOH can be reacted with CO₂ to form the carbonate product.

Repetitive cyclic voltammetry and galvanostatic cycling showed highly selective and stable electrochemical system for aqueous Li⁺ uptake and release. Overall, the hybrid electrochemical reactor is capable of selectively capturing Li⁺ at a fast rate and has a potential for high energy generation during the recovery process. Hence, this yielded an electrochemical Li recovery system that is environmentally benign and less energy intensive.

This research was supported by NRF funded by the Ministry of Science, ICT and future Planning (2017R1A2B2002109 and 2015R1A2A1A15055407) and the Ministry of Education (2009-0093816).